CD5 and leukemia: WHO-HAEM5 introduced the term splenic B-cell lymphoma/leukemia with prominent nucleoli to encompass most cases that would otherwise be designated hairy cell leukemia variant as well as cases of CD5-negative prolymphocytic leukemia.(18) The diagnosis of splenic B-cell lymphoma/leukemia with prominent nucleoli can be made in patients known to have splenomegaly, with circulating B-lineage neoplastic cells with the appropriate cytomorphology.